Your therapist has offered this, you can contact them. Their limit around contact is their boundary to look after, not yours. Your part of the boundary is to consider what your limits look like and to act in a way which meets your needs.

Personally, I wouldn't worry about only contacting them in a crisis or being distressed "enough" to justify contacting them. There are many reasons you might want contact with them and they are valid reasons. Wanting human contact from someone who shows you care and warmth is absolutely understandable. It sounds as if your therapist is happy to accept that. You are not toxic and an email from you will not ruin her holiday.